There is provided a process for preparing short chain alkyl aromatic compounds by alkylating or transalkylating an aromatic compound with an alkylating or transalkylating agent employing a particular acidic solid material as a catalyst. This acidic solid comprises a Group IVB metal oxide, such as zirconia, modified with an oxyanion of a Group VIB metal, such as tungstate.
The alkylation of aromatic hydrocarbons with an olefin in the presence of a zeolite having uniform pore openings of from about 6 to about 15 Angstrom units is described in U.S. Pat. No. 2,904,607. U.S. Pat. No. 3,251,897 describes the liquid phase alkylation of aromatic hydrocarbons in the presence of X- or Y-type zeolites, specifically such zeolites wherein the cation is a rare earth metal species and/or hydrogen. U.S. Pat. Nos. 3,751,504 and 3,751,506 describe the vapor phase alkylation of aromatic hydrocarbons with olefins, e.g., benzene with ethylene, in the presence of catalyst comprising, for example, ZSM-5.
U.S. Pat. Nos. 3,631,120 and 3,641,177, describe a liquid phase process for the alkylation of aromatic hydrocarbons with olefins in the presence of certain zeolites.
U.S. Pat. Nos. 4,962,256; 4,992,606; 4,954,663; 5,001,295; and 5,043,501, each incorporated herein by reference in its entirety, teach alkylation of aromatic compounds with various alkylating agents over catalyst comprising a particular crystalline material, such as PSH-3 or MCM-22. U.S. Pat. No. 4,962,256 describes preparing long chain alkylaromatic compounds by alkylating an aromatic compound with a long chain alkylating agent. U.S. Pat. No. 4,992,606 describes preparing short chain alkylaromatics by alkylating an aromatic compound with a short chain alkylating agent. U.S. Pat. No. 4,954,663 teaches alkylation of phenols, and U.S. Pat. No. 5,001,295 teaches alkylation of naphthalene. U.S. Pat. No. 5,043,501 describes preparation of 2,6-dimethylnaphthalene.
U.S. Pat. Nos. 3,755,483 and 4,393,262 disclose the vapor phase reaction of propylene with benzene in the presence of zeolite ZSM-12, to product isopropylbenzene.
U.S. Pat. No. 4,469,908 discloses the alkylation of aromatic hydrocarbons with relatively short chain alkylating agents having from 1 to 5 carbon atoms employing ZSM-12 as alkylation catalyst.
Harper et al. have described a catalytic alkylation of benzene with propylene over a crystalline zeolite (Petrochemical Preprints, American Chemical Society, vol. 22, no. 3, 1084 (1977)). Extensive kinetic and catalyst aging studies were conducted with a rare earth exchanged Y-type zeolite (REY) catalyst.
Ethylbenzene is a valuable commodity chemical which is currently used on a large scale industrially for the production of styrene monomer. Ethylbenzene may be produced by a number of different chemical processes but one process which has achieved a significant degree of commercial success is the vapor phase alkylation of benzene with ethylene in the presence of a solid, acidic ZSM-5 zeolite catalyst. In the production of ethylbenzene by this process, ethylene is used as the alkylating agent and is reacted with benzene in the presence of the catalyst at temperatures which vary between the critical temperature of benzene up to 900.degree. F. (about 480.degree. C.) at the reactor inlet. The reactor bed temperature may be as much as 150.degree. F. (about 85.degree. C.) above the reactor inlet temperature and typical temperatures for the benzene/ethylene reaction vary from 600.degree. to 900.degree. F. (315.degree. to 480.degree. C.), but are usually maintained above about 700.degree. F.(about 370.degree. C.) in order to keep the content of the more highly alkylated benzenes such as diethylbenzene at an acceptably low level. Pressures typically vary from atmospheric to 3000 psig (about 20785 kPa abs) with a molar ratio of benzene to ethylene from about 1:1 to 25:1, usually about 5:1 (benzene:ethylene). Space velocity in the reaction is high, usually in the range of 1 to 6, typically 2 to 5, WHSV based on the ethylene flow, with the benzene space velocity varying accordingly, in proportion to the ratio of the reactants. The products of the reaction include ethylbenzene which is obtained in increasing proportions as temperature increases together with various polyethylbenzenes, principally diethylbenzene (DIEB) which also are produced in increasing amounts as reaction temperature increases. Under favorable operating conditions on the industrial scale, an ethylene conversion in excess of 99.8 weight percent may be obtained at the start of the cycle.
In a commercial operation of this process, the polyalkylated benzenes, including both polymethylated and polyethylated benzenes are recycled to the alkylation reactor in which the reaction between the benzene and the ethylene takes place. By recycling the by-products to the alkylation reaction, increased conversion is obtained as the polyethylated benzenes (PEB) are converted to ethylbenzene (EB). In addition, the presence of the PEB during the alkylation reaction reduces formation of these species through equilibration of the components because at a given feed composition and under specific operating conditions, the PEB recycle will reach equilibrium at a certain level. This commercial process is known as the Mobil/Badger process and is described in more detail in an article by Francis G. Dwyer, entitled "Mobil/Badger Ethylbenzene Process-Chemistry and Catalytic Implications", appearing on pages 39-50 of a book entitled Catalysis of Organic Reactions, William R. Moser, ed., Marcel Dekker, Inc. (1981).
Ethylbenzene production processes are described in U.S. Pat. Nos. 3,751,504 (Keown); 4,547,605 (Kresge); and 4,016,218 (Haag); reference is made to these patents for a detailed description of such processes. The process described in U.S. Pat. No. 3,751,504 is of particular note since it includes a separate transalkylation step in the recycle loop which is effective for converting a significant proportion of the more highly alkylated products to the desired ethylbenzene product. Other processes for the production of ethylbenzene are disclosed in U.S. Pat. Nos. 4,169,11 (Wight) and 4,459,426 (Inwood), in both of which a preference for large pore size zeolites such as zeolite Y is expressed, in distinction to the intermediate pore size zeolites used in the processes described in the Keown, Kresge, and Haag patents. U.S. Pat. No. 3,755,483 (Burress) describes a process for the production of ethylbenzene using zeolite ZSM-12 as the alkylation catalyst.
Ethylbenzene (EB) can be synthesized from benzene and ethylene (C.sub.2 =) over a variety of zeolitic catalysts in either the liquid phase or in the vapor phase. An advantage of a liquid phase process is its low operating temperature and the resulting low content of by-products.
U.S. Pat. No. 4,891,458 describes the liquid phase synthesis of ethylbenzene and cumene with zeolite beta.
U.S. Pat. No. 5,149,894 describes the liquid phase synthesis of ethylbenzene and cumene with a crystalline aluminosilicate material designated SSZ-25.